IPTEL WG R. Mahy, Ed. Internet-Draft Cisco Systems, Inc. Expires: August 16, 2004 February 16, 2004 The Calling Party's Category tel URI Parameter draft-mahy-iptel-cpc-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 16, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document specifies a new parameter for the tel URI that represents the Calling Party's Category, a parameter used in SS7 ISUP signaling. 1. Introduction SS7 ISUP [3] defines a Calling Party's Category (CPC) parameter that characterizes the station used to originate a call and carries other important state that can describe the originating party. When telephone numbers are contained in URIs, such as the tel URI [1], it may be desirable to communicate any CPC associated with that telephone number or, in the context of a call, the party calling from it. Mahy Expires August 16, 2004 [Page 1] Internet-Draft CPC tel URI February 2004 Note that in some networks (including North America), the Originating Line Information (OLI) parameter is used to carry this information in ISUP rather than the CPC parameter. Legacy multifrequency (MF) signaling networks carry this information in the ANI II Digits [7]. The tel URI parameter specified in this document is designed to carry data from these sources as well. 2. Parameter Definition The Calling Party's Category is represented as a tel URI parameter. The ABNF [2] syntax is as follows: cpc = cpc-tag "=" cpc-value cpc-tag = "cpc" cpc-value = string CPC values ("cpc-value" strings) must be registered with IANA. The following values are pre-registered by this document: ordinary: The caller has been identified, and has no special features. priority: This call has priority/emergency status. data: This call will contain voice-band data. test: This is a test call that has been originated as part of a maintenance procedure. operator: The call was generated by an operator position. payphone: The calling station is a payphone. prison: The calling station is in a prison. hotel: The calling station is in a hotel or motel. (This value is currently used in ANI II.) unknown: The CPC could not be ascertained. In addition to the list above, the authors may consider inclusion of the following additional values if a stable reference which describes their use can be provided. hospital: The calling station is in a medical facility. Mahy Expires August 16, 2004 [Page 2] Internet-Draft CPC tel URI February 2004 police: The calling station is associated with a branch of law enforcement. cellular: The calling station is a radio-telephone operating in its home network. cellular-roaming: The calling station is a radio-telephone roaming in another network An example of the syntax of the CPC parameter (in a small fragment of a SIP [5] message) is given below: INVITE sip:bob@biloxi.example.com SIP/2.0 To: "Bob" From: ;tag=1928301774 3. Usage The CPC is generally useful only when describing the originator of a telephone call. Therefore, when this parameter is used in an application such as SIP, it is recommended that the parameter be applied to URIs that characterize the originator of a call (such as a SIP URI or tel URI in the From header field of a SIP message). Note that many Calling Party Category values from the PSTN were intentionally excluded from the cpc parameter as they are either meaningless outside of the PSTN or can be represented using another existing concept. For example, the language of an operator can be expressed more richly using the Accept-Language header in SIP than in the cpc parameter. It is anticipated that this URI will be used primarily by gateways that interwork ISUP networks with SIP networks. Various SIP network intermediaries might consult the CPC as they make routing decisions, although no specific behavior is prescribed in this document. While no specific mapping of the various ISUP parameters that contain CPC data is offered in this document, creating such a mapping would be trivial. If the CPC parameter is not present, consumers of the CPC should treat the URI as if it specified a CPC of "unknown". Generally, only one instance of the CPC will be associated with a particular URI. 4. Security Considerations The information contained in the CPC parameter may be of a private Mahy Expires August 16, 2004 [Page 3] Internet-Draft CPC tel URI February 2004 nature, and it may not be appropriate for this value to be revealed to the destination user (typically it would not be so revealed in the PSTN). For more information about Privacy issues in SIP see RFC3323 [6]. Otherwise, this mechanism adds no new security considerations to those discussed in [1]. 5. IANA Considerations This document requests the creation of an IANA registry for Calling Party's Category values. The values of the CPC parameter in use in ISUP are unfortunately quite specific to national networks, and thus it is very difficult to uncover all the usages that may be in place in various networks. Note that in North American networks, the Originating Line Information parameter contains information common found in the Calling Party's Category elsewhere; it is therefore legitimate to register values associated with the Originating Line Information in this registry. In order to file a registration, interested parties must contact IANA and supply them with both a new "cpc-value" and a short reason phrase describing the usage of the new CPC. Some values are given in Section 2; we ask that these values be pre-registered upon publication of this document as an RFC. It is not expected that this registry will require any expert supervision. 6. Contributors The original version of this document was written by Jon Peterson. Normative References [1] Schulzrinne, H. and A. Vaha-Sipila, "The tel URI for Telephone Calls", draft-antti-2806bis-08.txt (work in progress), Feb 2003. [2] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [3] International Telecommunications Union, "Recommendation Q.763: Signalling System No. 7: ISDN user part formats and codes", September 1997, . Informational References [4] Vaha-Sipila, A., "URLs for Telephone Calls", RFC 2806, April 2000. Mahy Expires August 16, 2004 [Page 4] Internet-Draft CPC tel URI February 2004 [5] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [6] Peterson, J., "A Privacy Mechanism for the Session Initiation Protocol (SIP)", RFC 3323, November 2002. URIs [7] Author's Address Rohan Mahy (editor) Cisco Systems, Inc. 5617 Scotts Valley Dr Scotts Valley, CA 95066 USA EMail: rohan@cisco.com Mahy Expires August 16, 2004 [Page 5] Internet-Draft CPC tel URI February 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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